Many image processing applications, such as image capture from a video signal, involve the conversion of a source image signal to a different signal for display on a computer monitor. For example, in some applications, incoming data is captured from a multi-dimensional colorspace signal, such as a YIQ signal or a Y, R-Y, B-Y signal, both of which are standard television transmission signals. The data is processed in that format. Before display, the data must be converted to a red, green, blue (RGB) format because the computer monitor, typically a cathode ray tube (CRT), expects the computer or other display driver to provide separate RGB signals.
The mathematical transformation required for this type of conversion from one colorspace to another requires a substantial amount of processing power. For YIQ to RGB conversion, 9 multiplies and 6 adds are required per pixel. Thus, 640.times.480.times.30.times.9 multiplies and 55 million adds per second are required to convert a YIQ television signal following the NTSC standard to an RGB signal for a typical monitor. For Y, R-Y, B-Y to RGB conversion, 3 multiplies and 4 adds are required per pixel.
The matrix calculations for such mathematical transformations are known in the art of image processing. An example of the mathematics for a YIQ to RGB conversion is set out in Hall, Illumination and Color in Computer Generated Imaging, p. 133, Springer-Verlag (1989).
One approach to image data conversion is the use of palettes, which are essentially look-up tables. In applications that do not involve colorspace to colorspace conversions, palettes are used to convert one-dimensional computer generated image data to other one dimensional data, i.e., greyscale data, or to convert one dimensional data to three dimensional data, i.e., RGB data.
However, for color conversion for photographic type pictures, conversion from a three dimensional color space to a different three dimensional space is required.
A need exists for a method of colorspace conversion that does not unduly burden the overall processing capacity of the computer system.